The present invention relates to a container for a semiconductor sensor and a method for manufacturing thereof, and a semiconductor sensor device. In particular, the present invention relates to technology that is favorably applied to a pressure sensor for an automobile.
A pressure sensor device for an automobile generally uses a semiconductor pressure sensor chip, in which piezoresistance effect is utilized. The semiconductor pressure sensor comprises a plurality of bridge-connected semiconductor strain gauges disposed on a diaphragm of single crystal silicon, for example. The strain gauge is made of a material exhibiting piezoresistance effect. Gauge resistance of the semiconductor strain gauges varies with deformation of the diaphragm due to the pressure variation. The resistance variation is taken out from the bridge circuit as a voltage signal.
FIG. 16 is a cross sectional view of a conventional semiconductor pressure sensor device. The pressure sensor device comprises a housing body 11 containing a semiconductor pressure sensor chip 13 in a sensor mounting pit 12 that is a well-shaped portion formed in the housing body, and a cover 14 that covers the housing body. The pressure sensor chip 13 is electrically connected through bonding wires 16 to lead terminals 15 for leading out. The lead terminals 15 that are lead frames are integrally insert-molded penetrating through the housing body 11. The surface of the pressure sensor chip 13 and the bonding wire 16 are protected by gel protective material 17 from adhesion of contaminant included in the medium for pressure measurement.
The pressure sensor chip 13 is fixed on a pedestal 18 made of glass. The pedestal 18 is provided for preventing the thermal expansion of the housing body 11 from adversely affecting the pressure sensor chip 13. Accordingly, certain thickness is required by the pedestal. The pedestal 18 is glued to the bottom of the sensor-mounting pit 12 with adhesive 19. The cover 14 has a pressure inlet hole 21 that connects a space, of which the pressure is to be measured, and a pressure detection room 20 located between the housing body 11 and the cover 14.
However, in the conventional pressure sensor device as described above, the gel protective material 17 may overflow or ooze out from the pressure detection room 20 before attaching the cover 14 to the housing body 11. The overflow causes defective adhesion of the cover 14 with the housing body 11, which raises problems of insufficient adhesion strength and imperfect gas-tightness.
Because of large difference in the amounts of thermal expansion in the housing body 11 of resin and the lead terminal 15, a slight clearance may be generated between the housing body 11 and the lead terminal 15 due to the shrinkage after the insert-molding. This clearance causes leakage of pressure in calibration of measuring pressure value in the manufacturing process of the pressure sensor device. That is a trouble to interfere with correct calibration. In addition, the leakage of the gel protective material 17 through the clearance causes degradation of the product.
The sensor-mounting pit 12 has a tapered shape being narrower in the bottom region, in order to facilitate mounting a sensor unit consisting of a pressure sensor chip 13 and the pedestal 18. Along the narrow gap between the sensor-mounting pit 12 and the pedestal 18, adhesive 18 may creep up by capillary action or thixotropy. The creeping up of the adhesive 19 reduces effective thickness of the pedestal 18, hindering enough stress relaxation. Thus, a problem is raised that performance of the pressure measurement is degraded by the influence of thermal expansion of the housing body 11.
The present invention has been made in view of the above problems because it would be desirable to avoid defective adhesion of the cover due to overflow of the gel protective material. it would further be desirable to get rid of a clearance between the housing body and the lead terminal. Still further, it would be desirable to suppress creeping up of the adhesive along the pedestal that fixes the semiconductor sensor element.
In accordance with the present invention, a container for a semiconductor sensor of the present invention comprises a groove on a surface portion of a housing body inside of a position contacting with a cover and outside of a housing hollow so that the groove is disposed surrounding the housing hollow and traps the gel protective material that overflows from the housing hollow. According to the construction of the invention, the overflowed gel protective material is trapped within the groove of the housing body.
A housing body of a container for a semiconductor sensor according to the present invention is provided with a recess portion or a protruding portion surrounding outside of a housing hollow on a portion of the housing body that contacts with a cover, while the cover is provided with a protruding portion or a recess portion that engages the recess portion or the protruding portion of the housing body respectively. According to this feature of the present invention, the recess portion or the protruding portion of the housing body engages the protruding portion or the recess portion of the cover, when the cover is adhered to the housing body.
In a container for a semiconductor sensor of the present invention, clearance between an outer surface of the housing body and a lead terminal is filled with filler such as resin. Clearance between the lead terminal and the housing body at the interior region of the housing body is filled by enclosing a portion of the lead terminal that contacts to an inner part of the housing body with filler such as resin. According to this feature of the invention, a gap between the housing body and the lead terminal is filled with filler.
In a container for a semiconductor sensor of the invention, the inner portion of the housing body is provided with a relief portion for excess adhesive to be released, the adhesive being supplied for fixing a sensor element in the housing hollow. According to this feature of the invention, the excess adhesive in fixing the sensor element runs out to the relief portion.